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Vieyra E, Calderón R, Linares R, Rosas G, Ramírez DA, Espinoza JA, Chaparro A, Silva CC, Domínguez R, Morales-Ledesma L. Pharmacologic blockade of nicotinic receptors in the suprachiasmatic nucleus increases ovarian atresia and inhibits follicular growth. J Neuroendocrinol 2024:e13421. [PMID: 38826071 DOI: 10.1111/jne.13421] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/24/2023] [Revised: 05/16/2024] [Accepted: 05/21/2024] [Indexed: 06/04/2024]
Abstract
Reproduction in all mammalian species depends on the growth and maturation of ovarian follicles, that is, folliculogenesis. Follicular development can culminate with the rupture of mature follicles and the consequent expulsion of their oocytes (ovulation) or in atresia, characterized by the arrest of development and eventual degeneration. These processes are regulated by different neuroendocrine signals arising at different hypothalamic nuclei, including the suprachiasmatic nucleus (SCN). In the later, the activation of muscarinic receptors (mAChRs) and nicotinic receptors (nAChRs) by acetylcholine is essential for the regulation of the pre-ovulatory signals that stimulate the rupture of mature follicles. To evaluate the participation of the nAChRs in the SCN throughout the oestrous cycle in the regulation of the hypothalamic-pituitary-ovarian axis. For this purpose, 90-day-old adult female rats in metoestrus, dioestrus, proestrus or oestrus were microinjected into the left- or right-SCN with 0.3 μL of saline solution as vehicle or with 0.225 μg of mecamylamine (Mec), a non-selective antagonist of the nicotinic receptors, diluted in 0.3 μL of vehicle. The animals were sacrificed when they presented vaginal cornification, indicative of oestrus stage, and the effects of the unilateral pharmacological blockade of the nAChRs in the SCN on follicular development, ovulation and secretion of oestradiol and follicle-stimulating hormone (FSH) were evaluated. The microinjection of Mec decreased the serum levels of FSH, which resulted in a lower number of growing and healthy follicles and an increase in atresia. The higher percentage of atresia in pre-ovulatory follicles was related to a decrease in the number of ova shed and abnormalities in oestradiol secretion. We also detected asymmetric responses between the left and right treatments that depended on the stage of the oestrous cycle. The present results allow us to suggest that during all the stages of the oestrous cycle, cholinergic signals that act on the nAChRs in the SCN are pivotal to modulate the secretion of gonadotropins and hence the physiology of the ovaries. Further research is needed to determine if such signals are generated by the cholinergic neurons in the SCN or by cholinergic afferents to the SCN.
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Affiliation(s)
- Elizabeth Vieyra
- Physiology of Reproduction Laboratory, Biology of Reproduction Research Unit, Facultad de Estudios Superiores Zaragoza, Universidad Nacional Autónoma de México, Mexico City, Mexico
- Chronobiology of Reproduction Research Lab, Biology of Reproduction Research Unit, Facultad de Estudios Superiores Zaragoza, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - Roberto Calderón
- Physiology of Reproduction Laboratory, Biology of Reproduction Research Unit, Facultad de Estudios Superiores Zaragoza, Universidad Nacional Autónoma de México, Mexico City, Mexico
- Chronobiology of Reproduction Research Lab, Biology of Reproduction Research Unit, Facultad de Estudios Superiores Zaragoza, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - Rosa Linares
- Laboratorio de Endocrinología, Biology of Reproduction Research Unit, Facultad de Estudios Superiores Zaragoza, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - Gabriela Rosas
- Physiology of Reproduction Laboratory, Biology of Reproduction Research Unit, Facultad de Estudios Superiores Zaragoza, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - Deyra A Ramírez
- Facultad de Estudios Superiores Zaragoza Campus III, UNAM, Tlaxcala, Mexico
| | - Julieta A Espinoza
- Physiology of Reproduction Laboratory, Biology of Reproduction Research Unit, Facultad de Estudios Superiores Zaragoza, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - Andrea Chaparro
- Physiology of Reproduction Laboratory, Biology of Reproduction Research Unit, Facultad de Estudios Superiores Zaragoza, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - Carlos-Camilo Silva
- Chronobiology of Reproduction Research Lab, Biology of Reproduction Research Unit, Facultad de Estudios Superiores Zaragoza, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - Roberto Domínguez
- Chronobiology of Reproduction Research Lab, Biology of Reproduction Research Unit, Facultad de Estudios Superiores Zaragoza, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - Leticia Morales-Ledesma
- Physiology of Reproduction Laboratory, Biology of Reproduction Research Unit, Facultad de Estudios Superiores Zaragoza, Universidad Nacional Autónoma de México, Mexico City, Mexico
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Guerrero-Vargas NN, Espitia-Bautista E, Escalona R, Lugo-Martínez H, Gutiérrez-Pérez M, Navarro-Espíndola R, Setién MF, Boy-Waxman S, Retana-Flores EA, Ortega B, Buijs RM, Escobar C. Timed restricted feeding cycles drive daily rhythms in female rats maintained in constant light but only partially restore the estrous cycle. Front Nutr 2022; 9:999156. [PMID: 36204367 PMCID: PMC9531653 DOI: 10.3389/fnut.2022.999156] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2022] [Accepted: 08/29/2022] [Indexed: 11/24/2022] Open
Abstract
Light at night is an emergent problem for modern society. Rodents exposed to light at night develop a loss of circadian rhythms, which leads to increased adiposity, altered immune response, and increased growth of tumors. In female rats, constant light (LL) eliminates the estrous cycle leading to a state of persistent estrus. The suprachiasmatic nucleus (SCN) drives circadian rhythms, and it interacts with the neuroendocrine network necessary for reproductive function. Timed restricted feeding (RF) exerts a powerful entraining influence on the circadian system, and it can influence the SCN activity and can restore rhythmicity or accelerate re-entrainment in experimental conditions of shift work or jet lag. The present study explored RF in female rats exposed to LL, with the hypothesis that this cyclic condition can rescue or prevent the loss of daily rhythms and benefit the expression of the estrous cycle. Two different feeding schedules were explored: 1. A 12-h food/12-h fasting schedule applied to arrhythmic rats after 3 weeks in LL, visualized as a rescue strategy (LL + RFR, 3 weeks), or applied simultaneously with the first day of LL as a preventive strategy (LL + RFP, 6 weeks). 2. A 12-h window of food intake with food given in four distributed pulses (every 3 h), applied after 3 weeks in LL, as a rescue strategy (LL + PR, 3 weeks) or applied simultaneously with the first day of LL as a preventive strategy (LL + PP, 6 weeks). Here, we present evidence that scheduled feeding can drive daily rhythms of activity and temperature in rats exposed to LL. However, the protocol of distributed feeding pulses was more efficient to restore the day–night activity and core temperature as well as the c-Fos day–night change in the SCN. Likewise, the distributed feeding partially restored the estrous cycle and the ovary morphology under LL condition. Data here provided indicate that the 12-h feeding/12-h fasting window determines the rest-activity cycle and can benefit directly the circadian and reproductive function. Moreover, this effect is stronger when food is distributed along the 12 h of subjective night.
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Affiliation(s)
- Natalí N. Guerrero-Vargas
- Departamento de Anatomía, Facultad de Medicina, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | | | - Rene Escalona
- Departamento de Embriología y Genética, Facultad de Medicina, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - Haydée Lugo-Martínez
- Departamento de Embriología y Genética, Facultad de Medicina, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - Mariana Gutiérrez-Pérez
- Departamento de Anatomía, Facultad de Medicina, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - Raful Navarro-Espíndola
- Departamento de Anatomía, Facultad de Medicina, Universidad Nacional Autónoma de México, Mexico City, Mexico
- Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - María Fernanda Setién
- Departamento de Anatomía, Facultad de Medicina, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - Sebastián Boy-Waxman
- Departamento de Anatomía, Facultad de Medicina, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | | | - Berenice Ortega
- Departamento de Anatomía, Facultad de Medicina, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - Ruud M. Buijs
- Departamento de Fisiología Celular y Biología, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - Carolina Escobar
- Departamento de Anatomía, Facultad de Medicina, Universidad Nacional Autónoma de México, Mexico City, Mexico
- *Correspondence: Carolina Escobar,
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